Math practice for 13 year olds - page 168 of 428
Number of problems found: 8558
- Brass ball
What is the weight of a hollow brass ball, the outer diameter of which is 16 cm and the wall thickness is 2 cm, while the density of brass is ϱ = 8.5 g - Cindy run
Suppose it takes 1/3 of an hour for Cindy to run 3/5 of a mile. How many miles does she run in 1 hour? - Shot casting
How many shots with a diameter of 2 mm can a gunsmith cast from 1 kg of lead? The density of lead is 11.4 g / cm3 - Ball drawing probability
We have five red and seven white balls in a hat. What is the probability of pulling: a) a red ball? b) a white ball? - No solutions
Why does the equation 9-2x-9-16x=-14x-7-4x-11 have no solutions? - The difference 2
The difference between the two numbers is 25. The smaller number is 1/6th of the larger number. What is the value of the smaller number? - Reindeer penguin
There were 10 more reindeer than penguins in the ice kingdom. But the lousy witch captured a third of the reindeer. There were only 22 reindeer left in the kingdom. How many penguins lived in the ice kingdom before the evil witch came? - Dice roll probability
What is the probability of a random event A that a) an even number, b) a number divisible by three, c) a number greater than six will fall on the dice roll. - Odd prime probability
What is the probability that an odd prime will fall on a dice roll? - Odd compound probability In the entertainment lottery, they draw one number from 1 to 35. What is the probability that they will draw an odd compound number?
- Boy selection probability
Six boys and nine girls played in the school group. What probability will they point to the boy when they are reproached? - Pyramid surface volume
A quadrilateral pyramid has a square base 4 cm long, the height of the pyramid 5 cm, and the height of the wall 5.4 cm. Find the surface and volume of a quadrilateral pyramid. - Apples investment
The merchant bought a certain amount of apples and paid one denarius for every seven apples. The next day he sold all the apples for one denarius for five pieces and earned 12 denarii. How many apples did he originally buy, and how many did he have to inv - Land acre purchase
The price for 1 acre of good land is 300 gold coins, and the price for 7 acres of bad land is 500 gold. The buyer bought a total of 100 acres for 10,000 guilders. How many acres of good and how many acres of bad land did he buy? - A plane vs. sphere
The intersection of a plane is 2 cm from the sphere's center, and this sphere is a circle whose radius is 6 cm. Calculate the surface area and volume of the sphere. - Pigs
A buyer said, "I want to buy 100 pigs for 100 denarii. An adult pig costs ten denarii, a sow five denarii, and two little piglets are worth one denarius. " How many pigs, cows, and piglets could he buy for exactly 100 denarii? - Triangle area percentage
A right-angled triangle ABC has sides a = 5 cm, b = 8 cm. The similar triangle A'B'C' is 2.5 times smaller. Calculate the percentage of the area of triangle ABC that is the area of triangle A'B'C'. - Strawberry harvest
Thirty-six women earned € 2,640 in 5 days during the strawberry harvest. How much € 24 will women earn in 8 days under the same conditions? - Height - the ladder
At what height does the 15 m ladder touch the wall if its lower end is 2.5 m away from it? - Largest possible cone
It is necessary to make the largest possible cone from an iron rod in the shape of a prism with dimensions of 5.6 cm, 4.8 cm, and 7.2 cm. a) Calculate its volume. b) Calculate the waste.
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